This disclosure relates to polyester compositions, method of manufacture, and articles thereof.
Thermoplastic polyester compositions, such as poly(alkylene terephthalates), have valuable characteristics including strength, toughness, high gloss, and solvent resistance. Polyesters therefore have utility as materials for a wide range of applications, from automotive parts to electric and electronic appliances. Because of their wide use, particularly in electronic applications, it is desirable to provide flame retardancy to polyesters.
Numerous flame retardants (FR) for polyesters are known, but many contain halogens, usually chlorine and/or bromine. Halogenated flame retardant agents are less desirable because of the increasing demand for ecologically friendly ingredients. Halogen-free flame retardants, such as phosphorus- and nitrogen-based compounds can be used as well. Unfortunately, they lack good flame retardancy in thin sections.
More ecologically compatible flame retardant (eco-FR) formulations based on aluminum salts of phosphinic or diphosphinic acid compounds and melamine compounds have been developed to overcome environmental issues of halogenated flame retardants. However, the formulations also possess undesirable mechanical properties, including reduced impact strength and tensile strength, as well as undesirable flow properties compared to the halogenated flame retardant compositions.
An ongoing need exists for polyester compositions, particularly from recycled polyester, having the combination of good flame retardant properties not only at thicknesses of 1.5 mm or greater, but also at thicknesses of 0.8 mm or less. It would be advantageous if this combination of flame retardant properties could be achieved while at least essentially maintaining mechanical properties and/or heat properties.